1. Field of the Invention
This invention relates to fluid filters and more specifically to lubricant filters used for automatic transmissions such as those used in conjunction with internal combustion engines.
2. Related Art
It is well established that the life of mechanical equipment is dependent on the quality of the lubricating fluid, i.e. the lubricant. The quality of lubricant, and in the case of automatic transmissions, the power transfer fluid, is assured by periodic lubricant replacement and thorough and continuous filtering of undesired foreign matter from the fluid.
The conventional approach for filtering the power transfer and lubrication fluid used in automatic transmissions is to include the entire filter system within the transmission housing. As a result, changing or cleaning a filter requires removing and replacing the lower portion of the housing, i.e. the pan (or sump). This is a very time consuming process that is most frequently performed by professional automotive transmission specialists. In addition, because of the difficulty and expense of changing these conventional filter systems, vehicle operators frequently delay filter changes well beyond recommended mileage intervals, or even worse, they avoid changing the filters altogether. This can lead to premature failure of the transmission thus incurring repair or replacement costs of several hundred or even thousands of dollars. Furthermore, by removing the pan, the risk of creating undesired transmission fluid leaks through a damaged pan gasket is substantially increased. Of course the occurrence of such leaks is typically unknown until the transmission is operated sufficiently to achieve normal operational temperatures. Thus these leaks may go undetected for a long time. When the leak is finally detected, the pan must be removed a second time, losing substantial quantities of the fresh fluid lubricant, and a new gasket must be installed. This process is time consuming, wasteful, environmentally damaging, and costly.
Prior inventors are not known to have addressed this problem. Parker (U.S. Pat. No. 5,546,999) discloses new equipment for replenishing the lubricant of an automatic transmission. Parker connects his apparatus to an existing external fluid filter included in the transmission cooling line of a tractor. He does not address the issue of a convenient method of replacing automatic transmission fluid filters.
Ward (U.S. Pat. No. 3,784,011) provides improved filtering of automatic transmission fluid by incorporating a magnetic medium in a supplemental filter included within the automatic transmission housing.
Holmes (U.S. Pat. No. 4,689,144) discloses a new supplemental filter for automatic transmissions that incorporates both mechanical and magnetic filtering elements in a disposable filter. The filter is provided with fluid entry and exit spigots at opposite ends of a cylindrical casing. This external filter is preferably placed in the cooling supply line before the transmission-cooling radiator. Holmes"" filter is a new, unconventional design and thus not easily available commercially at this time. Furthermore, Holmes"" filter is not integral with the transmission housing and thus requires potentially unreliable connection points and fluid transmission hoses. And finally, Holmes"" filter is not easily replaced since it is of an unconventional design and is not adapted for a spin-on/spin-off installation and removal.
Thus, the objects of the extant invention are:
a. to provide a transmission lubricant filter that does not require removal of the transmission sump pan for its replacement,
b. to provide an transmission lubricant filter of the conventional spin-on/spin-off design that is external to the transmission,
c. to provide a transmission filter that is conveniently replaced,
d. to provide a transmission fluid/lubricant filter that filters all of the transmission lubricant that circulates through the lubricant pump,
e. to provide a more efficient transmission lubricant filter,
f. to provide a transmission filter that is easily adapted to any automatic transmission,
g. to provide a filtering concept that may be inexpensively incorporated into new transmission designs,
h. to provide a transmission filter that minimizes the loss of lubricant in the filter replacement process, and
i. to provide an automatic transmission filter that eliminates the leakage of fluid through the transmission sump pan gasket that may result from gasket damage during filter replacement.
As summarized in the previous discussion, there is a long felt and unfulfilled need for a means to conveniently, safely and effectively replace automatic transmission lubricant filters. To meet this need, the preferred embodiment of the extant invention provides an external lubricant filter system for automatic transmissions comprising a modified transmission lubricant pan assembly and an external spin on/off lubricant filter canister that is removably connected to the modified pan.
The transmission pan is modified to include a filter adapter in the wall of the pan. The filter adapter includes an externally threaded pipe nipple and sealing surface for removably and sealably receiving the filter canister. The adapter also includes a lubricant entry port and a lubricant inlet plenum for distributing the potentially contaminated lubricant to the inlet orifices of the filter canister.
The pan is further modified to incorporate a lubricant inlet chamber and a lubricant outlet chamber, both secured to the interior wall of the pan. This invention further includes a lubricant pick up assembly and a lubricant discharge tube. The lubricant pick up assembly delivers contaminated lubricant from the pan to the filter canister via the inlet chamber, and the entry port and plenum of the filter adapter. The discharge tube receives cleansed oil from the filter canister via the nipple and outlet chamber and delivers it to the inlet of the transmission""s lubricant pump.
In the preferred embodiment of this invention the filter canister is a conventional spin on/off oil filter. The modified pan may be formed by altering a factory stock pan, or preferably by altering an aftermarket product. Alternatively, the pan may be manufactured as an original equipment item that incorporates the novel features of this invention
In use, this invention revolutionizes the changing of automatic transmission fluid filters. Rather than having to remove the pan from the transmission, the filter canister is merely rotated counterclockwise to remove it from the pan while the pan remains attached to the transmission housing. The replacement filter is simply threaded clockwise onto the cooperating pipe nipple and sealed to the adapter via the seal supplied with the filter. In this fashion, the objectives of this invention are fully satisfied. The filter canister may be changed without removing the pan of the transmission, commercial off-the-shelf filters are used, all of the lubricant passing through the pump is filtered and loss of fluid during filter changing operations is minimized. Additionally, this invention may be retrofitted to existing automatic transmissions, or it may be incorporated in the original manufacture of the transmission.
These and many other features and attendant advantages of the invention will become apparent, as the invention becomes better understood by reference to the following detailed descriptions and accompanying drawings.